flask-migrate的使用-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_36646275/article/details/107662960

本文详细介绍了如何使用Flask-Migrate进行数据库迁移，包括初始化数据库、生成迁移脚本及执行升级过程。通过与Django的ORM对比，展示了Flask-Migrate在Flask应用中的强大功能。

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manager.py代码如下:

from flask_script import Manager, Shell, Server
from flask_migrate import Migrate, MigrateCommand
from app.ext import db
from app import create_app

app = create_app()

manager = Manager(app=app)
migrate = Migrate(app, db)


def make_shell_context():
	return dict(app=app)


manager.add_command("shell", Shell(make_context=make_shell_context))
manager.add_command("run_dev", Server(use_debugger=True, use_reloader=True))
manager.add_command("runserver", Server())
manager.add_command("db", MigrateCommand)


@manager.command
def deploy():
	"""run deployment tasks"""
	pass


if __name__ == "__main__":
	manager.run(default_command="runserver")

执行python manager.py db 查看参数说明

@MacBook-Pro-2 Garen % python manager.py db
usage: Perform database migrations

Perform database migrations

positional arguments:
  {init,revision,migrate,edit,merge,upgrade,downgrade,show,history,heads,branches,current,stamp}
    init                Creates a new migration repository
    revision            Create a new revision file.
    migrate             Alias for 'revision --autogenerate'
    edit                Edit current revision.
    merge               Merge two revisions together. Creates a new migration
                        file
    upgrade             Upgrade to a later version
    downgrade           Revert to a previous version
    show                Show the revision denoted by the given symbol.
    history             List changeset scripts in chronological order.
    heads               Show current available heads in the script directory
    branches            Show current branch points
    current             Display the current revision for each database.
    stamp               'stamp' the revision table with the given revision;
                        don't run any migrations

创建数据库操作

初始化数据库

init命令会创建一个新的版本仓库,并且会生成migrations文件夹.这点类似django.

(Garen) zhouwanghua@MacBook-Pro-2 Garen % python manager.py db init
  Creating directory /Users/zhouwanghua/Code/Garen/migrations ...  done
  Creating directory /Users/zhouwanghua/Code/Garen/migrations/versions ...  done
  Generating /Users/zhouwanghua/Code/Garen/migrations/script.py.mako ...  done
  Generating /Users/zhouwanghua/Code/Garen/migrations/env.py ...  done
  Generating /Users/zhouwanghua/Code/Garen/migrations/README ...  done
  Generating /Users/zhouwanghua/Code/Garen/migrations/alembic.ini ...  done
  Please edit configuration/connection/logging settings in '/Users/zhouwanghua/Code/Garen/migrations/alembic.ini'
  before proceeding.

创建version表

执行upgrade之后会在数据中创建一个alembic_version表

(Garen) zhouwanghua@MacBook-Pro-2 Garen % python manager.py db upgrade
INFO  [alembic.runtime.migration] Context impl MySQLImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.

生成models对象的迁移脚本

如果有新的表或字段改动都需要使用这个命令,类似django的makemigrations

(Garen) zhouwanghua@MacBook-Pro-2 Garen % python manager.py db migrate
INFO  [alembic.runtime.migration] Context impl MySQLImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.autogenerate.compare] Detected added table 'reply'
  Generating /Users/zhouwanghua/Code/Garen/migrations/versions/d5e95964b986_.py ...  done

在执行迁移命令upgrade

执行迁移脚本,创建/维护表

(Garen) zhouwanghua@MacBook-Pro-2 Garen % python manager.py db upgrade
INFO  [alembic.runtime.migration] Context impl MySQLImpl.
INFO  [alembic.runtime.migration] Will assume non-transactional DDL.
INFO  [alembic.runtime.migration] Running upgrade  -> d5e95964b986, empty message